Random Brief Internet Disconnects with Gigabit Internet

[chouinar]

Hey all,

I have been having an issue with random, brief (2-5 second) internet disconnects. Usually they appear to come in spurts (every few minutes for about 30 minutes), more commonly in the evening. I've experienced these issues on multiple devices: a PC, a MacBook, an Android phone and an Amazon FireTV. The PC and MacBook are both hardwired in on ethernet directly to the modem, and I've tried multiple ethernet cords as well. The other devices are over WiFi. When not experiencing a brief disconnect, I have no problems whatsoever in terms of speed or performance.

I had my internet installed at the end of April (all new coaxial cables going from the pole to my modem inside), and in the past 2-3 weeks have begun to experience these brief random disconnects.  The coaxial cable goes from the pole, has one female-to-female connector on the exterior of the house, and a splitter on the interior of the house. The splitter is an SV-2g 2-way splitter which doesn't appear to have any corrosion or other discoloration. The splitter does not have a second output, but due to it's placement (basement ceiling rafters), it's hard to plug the modem directly to the preceding cable.

The modem system logs only show logins/logouts, and the event logs don't show any errors:

[Harvester][3660]: Harvester StartRadioTrafficHarvesting Starting Thread to start RadioTraffic Data Harvesting2019/7/01 09:37:31Notice[Harvester][3660]: Harvester StartAssociatedDeviceHarvesting : Started Thread to start DeviceData Harvesting2019/7/01 09:37:31Notice[Harvester][3675]: Harvester StartRadioTrafficHarvesting Starting Thread to start RadioTraffic Data Harvesting2019/6/30 20:34:59Notice[Harvester][3675]: Harvester StartAssociatedDeviceHarvesting : Started Thread to start DeviceData Harvesting2019/6/30 20:34:59Notice

I noticed some odd events in my firewall logs, but no idea if they're significant. The timestamps don't correlate too closely with my issues, but they could be aggregated metrics. For what it's worth, I had an issue about an hour after the latest event, so not sure if this is relevant:

FW.IPv6 FORWARD drop , 14 Attempts, 2019/7/04 19:07:58	Firewall Blocked
FW.IPv6 FORWARD drop , 1701 Attempts, 2019/7/04 18:58:01	Firewall Blocked
FW.IPv6 INPUT drop , 110 Attempts, 2019/7/04 18:58:01	Firewall Blocked
FW.IPv6 INPUT drop , 36 Attempts, 2019/7/03 18:58:01	Firewall Blocked
FW.IPv6 FORWARD drop , 1690 Attempts, 2019/7/03 18:58:01	Firewall Blocked
FW.IPv6 FORWARD drop , 1621 Attempts, 2019/7/02 18:58:01	Firewall Blocked
FW.IPv6 INPUT drop , 33 Attempts, 2019/7/02 17:58:01	Firewall Blocked
FW.WANATTACK DROP , 2 Attempts, 2019/7/02 17:58:01	Firewall Blocked

 

Cable Modem

HW Version:2.2

Vendor:Technicolor

BOOT Version:S1TC-3.49.18.14

Core Version:1.0

Model:CGM4140COM

Product Type:XB6

Flash Part:8192 MB

Download Version:Prod_18.1_d31 & Prod_18.1

Downstream	Channel Bonding Value
Index	25	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	26	27	28	29	30	31	32	159
Lock Status	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked
Frequency	615 MHz	465 MHz	471 MHz	477 MHz	483 MHz	489 MHz	495 MHz	507 MHz	513 MHz	519 MHz	525 MHz	531 MHz	537 MHz	543 MHz	549 MHz	555 MHz	561 MHz	567 MHz	573 MHz	579 MHz	585 MHz	591 MHz	597 MHz	603 MHz	609 MHz	621 MHz	627 MHz	633 MHz	639 MHz	645 MHz	651 MHz	657 MHz	690 MHz	605600000
SNR	39.9 dB	41.0 dB	40.9 dB	40.8 dB	40.7 dB	40.7 dB	40.4 dB	40.3 dB	40.1 dB	40.3 dB	40.0 dB	40.3 dB	40.2 dB	40.1 dB	40.1 dB	40.1 dB	40.3 dB	40.5 dB	39.7 dB	39.6 dB	40.5 dB	40.2 dB	40.3 dB	40.3 dB	40.1 dB	39.3 dB	39.0 dB	39.6 dB	39.4 dB	38.5 dB	38.3 dB	37.8 dB	14.5 dB	NA
Power Level	-4.9 dBmV	-5.0 dBmV	-5.0 dBmV	-5.0 dBmV	-5.2 dBmV	-5.2 dBmV	-5.3 dBmV	-5.6 dBmV	-5.5 dBmV	-5.4 dBmV	-5.6 dBmV	-5.4 dBmV	-5.3 dBmV	-5.4 dBmV	-5.3 dBmV	-5.1 dBmV	-4.9 dBmV	-4.5 dBmV	-4.5 dBmV	-4.6 dBmV	-4.5 dBmV	-4.4 dBmV	-4.5 dBmV	-4.7 dBmV	-4.8 dBmV	-5.1 dBmV	-5.4 dBmV	-5.0 dBmV	-5.4 dBmV	-5.7 dBmV	-6.0 dBmV	-6.2 dBmV	-6.5 dBmV	NA
Modulation	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	OFDM	OFDM

Upstream	Channel Bonding Value
Index	1	2	3	4
Lock Status	Locked	Locked	Locked	Locked
Frequency	35 MHz	29 MHz	23 MHz	16 MHz
Symbol Rate	5120	5120	5120	5120
Power Level	46.3 dBmV	46.8 dBmV	46.3 dBmV	46.3 dBmV
Modulation	QAM	QAM	QAM	QAM
Channel Type	ATDMA	ATDMA	ATDMA	ATDMA

CM Error Codewords
Index	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31	32	33
Unerrored Codewords	2857796644	429270168	429277313	429281256	429284658	429291597	429296516	429302515	429347773	429354838	429362883	429365280	429370534	429378976	429383466	429388276	429533668	429539948	429543855	429548800	429555080	429559942	429563789	429568840	429574844	429581475	429586792	429591224	429596971	429602284	429605094	429607925	2857796644
Correctable Codewords	1486886916	6960	6704	6464	6481	6500	6917	5939	6210	5981	5420	5470	5365	5264	5311	4745	4481	4192	4035	4040	3681	3701	3825	3582	3354	3400	3460	3308	3002	3117	2963	3238	1486886916
Uncorrectable Codewords	15	6326	6267	6145	5846	6018	6099	5747	5632	5444	5585	5465	5445	5367	5027	5127	4992	4878	4897	4829	4775	4507	4415	4526	4581	4396	4356	4279	4214	4183	4179	4074	15

Note: the modem uptime is 3d, 9h at the time I copy this. So the uncorrectable error codes are cumulative for that amount of time.

[ComcastAmira]

Hello @chouinar, thanks for reaching out to our Forums! I'm sorry to hear about this connection issue you have been experiencing. I can imagine how frustrating and inconvenient this would be. I would be more than happy to assist and further troubleshoot this for you. Can you please send me a private message including the full name as it appears on the account and your full name if different? 

To send me a Private Message, please click my name “ComcastAmira” and click “send a message. 

[chouinar]

I reached out to Amira, but haven't received any sort of reply, just going to update here I guess.

I removed the splitter and a length of coaxial cable to see if that would help. I think I've seen fewer issues, but as it's a random issue, I can't say for certain (still not fixed though). Below are some of the updated router metrics for the past 24 hours.

I noticed the downstream power is better (seen it fluctuating between -2 and 0), but the upstream is still bouncing between 46 and 57ish and the 4th channel isn't locked, which I noticed before, although don't know what that means?

Still seeing a lot of uncorrectable errors, restarted the gateway just shy of 24h ago.

Downstream	Channel Bonding Value
Index	25	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	26	27	28	29	30	31	32	159
Lock Status	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked
Frequency	615 MHz	465 MHz	471 MHz	477 MHz	483 MHz	489 MHz	495 MHz	507 MHz	513 MHz	519 MHz	525 MHz	531 MHz	537 MHz	543 MHz	549 MHz	555 MHz	561 MHz	567 MHz	573 MHz	579 MHz	585 MHz	591 MHz	597 MHz	603 MHz	609 MHz	621 MHz	627 MHz	633 MHz	639 MHz	645 MHz	651 MHz	657 MHz	690 MHz	605600000
SNR	40.5 dB	41.7 dB	41.6 dB	41.6 dB	41.4 dB	41.4 dB	41.0 dB	40.9 dB	40.9 dB	41.0 dB	40.8 dB	40.9 dB	41.0 dB	40.8 dB	40.8 dB	40.9 dB	41.0 dB	41.1 dB	37.2 dB	40.1 dB	41.0 dB	40.4 dB	40.7 dB	40.9 dB	40.7 dB	31.4 dB	35.5 dB	39.1 dB	39.8 dB	38.9 dB	36.6 dB	35.4 dB	12.5 dB	NA
Power Level	-1.2 dBmV	-1.7 dBmV	-1.8 dBmV	-1.8 dBmV	-1.8 dBmV	-1.8 dBmV	-2.0 dBmV	-2.0 dBmV	-2.0 dBmV	-1.9 dBmV	-2.0 dBmV	-1.7 dBmV	-1.6 dBmV	-1.8 dBmV	-1.7 dBmV	-1.5 dBmV	-1.2 dBmV	0.9 dBmV	0.9 dBmV	-1.0 dBmV	0.9 dBmV	0.9 dBmV	0.8 dBmV	0.8 dBmV	-1.1 dBmV	-1.3 dBmV	-1.5 dBmV	-1.3 dBmV	-1.5 dBmV	-1.8 dBmV	-1.8 dBmV	-2.2 dBmV	-2.2 dBmV	NA
Modulation	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	OFDM	OFDM

Upstream	Channel Bonding Value
Index	1	2	3	4
Lock Status	Locked	Locked	Locked	Not Locked
Frequency	35 MHz	29 MHz	23 MHz	16 MHz
Symbol Rate	5120	5120	5120	5120
Power Level	52.3 dBmV	54.3 dBmV	55.8 dBmV	56.8 dBmV
Modulation	QAM	QAM	QAM	QAM
Channel Type	ATDMA	ATDMA	ATDMA	ATDMA

CM Error Codewords
Index	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31	32	33
Unerrored Codewords	3301133609	3824323449	3824329084	3824334732	3824340980	3824345349	3824348815	3824356627	3824371516	3824376581	3824381503	3824386714	3824391691	3824396961	3824400769	3824408094	3824442294	3824446691	3824451705	3824456817	3824462252	3824466127	3824472222	3824477021	3824481801	3824486817	3824491674	3824496928	3824502046	3824506214	3824507268	3824510493	3301133609
Correctable Codewords	139778797	7207	6423	5666	5353	4966	6176	4528	4246	3900	3969	3590	3433	3270	3142	3064	2476	2614	2749	2325	2323	2218	2291	2139	2089	2017	1952	1898	1865	1904	1770	1859	139778797
Uncorrectable Codewords	15	3327	3117	3136	2984	2959	2990	2852	2905	2764	2741	2616	2567	2551	2361	2351	2471	2403	2332	2267	2199	2250	2029	1997	2118	2001	1988	2096	1923	1785	1769	1723	15

[EG]

The upstream power is too high / out of spec. That can cause random disconnects, spontaneous re-booting of the modem, and speed and latency problems.

In a self troubleshooting effort to try to obtain better connectivity / more wiggle room, check to see if there are there any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Any splitters that remain should be high quality and cable rated for 5-1002 MHz, bi-directional, and no gold colored garbage types like GE, RadioShack, RCA, Philips, Leviton, Magnavox, and Rocketfish from big box stores like Home Depot, Lowes, Target, Wal-Mart etc. Splitters should be swapped with known to be good / new ones to test

If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two way splitter connected directly off of the drop from the street/pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed, and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct.

[ComcastAmira]

@chouinar, I offer my deepest apologies for the delay in response, I was off for the last few days. I hope the very useful information @EG provided was helpful. I have also responded to your private message and I will await your response. Thanks! 

[EG]

@chouinar 

Did you have a chance to try any of those tips ?

[chouinar]

I had a technician come out this morning to look into the issue. It seems when my internet was initially installed, they probably used a dull cutting tool for the coaxial cables, so the inner wire had an iffy connection.

The technician replaced all of the ends of the cables and my metrics seem much better. Need to give it some time to know for certain, but it initially feels much better.

Downstream	Channel Bonding Value
Index	25	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	26	27	28	29	30	31	32	159
Lock Status	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked	Locked
Frequency	615 MHz	465 MHz	471 MHz	477 MHz	483 MHz	489 MHz	495 MHz	507 MHz	513 MHz	519 MHz	525 MHz	531 MHz	537 MHz	543 MHz	549 MHz	555 MHz	561 MHz	567 MHz	573 MHz	579 MHz	585 MHz	591 MHz	597 MHz	603 MHz	609 MHz	621 MHz	627 MHz	633 MHz	639 MHz	645 MHz	651 MHz	657 MHz	690 MHz	605600000
SNR	41.3 dB	42.3 dB	42.3 dB	42.1 dB	42.2 dB	42.0 dB	41.8 dB	41.8 dB	41.7 dB	41.6 dB	41.4 dB	41.5 dB	41.5 dB	41.4 dB	41.4 dB	41.4 dB	41.6 dB	41.7 dB	41.0 dB	41.4 dB	41.7 dB	41.6 dB	41.5 dB	41.6 dB	41.4 dB	40.5 dB	40.8 dB	41.0 dB	40.9 dB	40.5 dB	40.1 dB	38.8 dB	14.9 dB	NA
Power Level	1.5 dBmV	1.1 dBmV	1.0 dBmV	1.0 dBmV	0.9 dBmV	0.9 dBmV	0.7 dBmV	0.8 dBmV	0.7 dBmV	0.7 dBmV	0.6 dBmV	0.9 dBmV	1.0 dBmV	0.8 dBmV	1.0 dBmV	1.1 dBmV	1.4 dBmV	1.8 dBmV	1.8 dBmV	1.8 dBmV	1.9 dBmV	2.0 dBmV	2.0 dBmV	2.0 dBmV	1.7 dBmV	1.4 dBmV	1.2 dBmV	1.4 dBmV	1.3 dBmV	1.3 dBmV	0.9 dBmV	0.3 dBmV	0.6 dBmV	NA
Modulation	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	256 QAM	OFDM	OFDM

Upstream	Channel Bonding Value
Index	1	2	3	4
Lock Status	Locked	Locked	Locked	Locked
Frequency	35 MHz	29 MHz	23 MHz	16 MHz
Symbol Rate	5120	5120	5120	5120
Power Level	41.3 dBmV	42.3 dBmV	41.8 dBmV	41.8 dBmV
Modulation	QAM	QAM	QAM	QAM
Channel Type	ATDMA	ATDMA	ATDMA	ATDMA

[EG]

Looks good ! Hope it holds up for you. Good luck !

[ComcastAmira]

@chouinar, I am very happy to hear that the technician was able to determine the cause of this issue and get it corrected. I will follow up with you next week in our private message just to make sure things are still looking good on your end. Please do reach out if you need any assistance in the meantime. I will talk to you soon and I hope you enjoy the rest of your weekend. 

[chouinar]

Unfortunately, while the metrics looked good initially, after a few hours, I started noticing a similar trend as before with brief disconnects.

Before I restarted my modem, I had ~3000 uncorrectable error codes (over just a four hour period) across every channel.

The upstream is still really jiterry, and isn't even a consistent power across channels (I've noticed this before as well):

Upstream	Channel Bonding Value
Index	1	2	3	4
Lock Status	Locked	Locked	Locked	Not Locked
Frequency	35 MHz	29 MHz	23 MHz	16 MHz
Symbol Rate	5120	5120	5120	5120
Power Level	52.3 dBmV	54.3 dBmV	45.3 dBmV	56.3 dBmV
Modulation	QAM	QAM	QAM	QAM
Channel Type	ATDMA	ATDMA	ATDMA	ATDMA

Some other metrics, did a ping test against google.com and had 11% packet loss. These came in bunches, the first ~80 requests succeeded, and then half of the next 20 failed.

Packets: Sent = 204, Received = 181, Lost = 23 (11% loss),
Approximate round trip times in milli-seconds:
Minimum = 15ms, Maximum = 111ms, Average = 20ms

I did a speed test, and will my download is great, I feel my upload should be a lot better than 3.8mbps:

http://speedtest.xfinity.com/results/1562968600153_JY0N5E5OAHUQ6ZD

[EG]

Uh-oh..... Yep, something intermittent is going on. Get the techs involved again until it is fixed properly.

[chouinar]

Yeah, I set up another tech visit for Sunday afternoon.

[chouinar]

Had the technician out earlier this afternoon. He redid the wiring from the pole to the house, but said the issue is almost certainly further up the network. I think he said from their side, they've seen 30ish restarts in the past 24 hours (I assume that means times my modem had to reconnect to xfinity). 

He said it's likely there is a leaky connection somewhere in my neighborhood that is causing issues, but that it could be any of a hundred different actual problems. He did find that one of the neighbors behind me had a connection tagged as leaky on the line, and did something on the pole to make it so I wasn't connected through that anymore, but did not promise that this would fix the issue as it might be a small part of the overall problem. He also mentioned that there could still be some issues this evening as it's very likely my modem's software is out of date due to all of the dropped connections, and that that would be corrected around 3am during the overnight update processes that get run.

So far, in the ~2 hours since the technician left, things have seemed fine, but we'll see. Probably would need a few days to know for certain due to the intermittent nature of the problem, but fingers crossed that it was just that one single issue at the pole. Will update in the next few days, good or bad.

As for anyone else having issues, I'd suggest getting a technician out as any issue similar to mine is purely hardware and requires a technician to correct.

[ComcastAmira]

Hello @joconnell97, thanks for reaching out to our Forums! I'm sorry to hear that you are also experiencing this connection issues on your end. I absolutely understand how important playing Fortnight is to kids. I definitely want to further investigate this on my end and get a tech out if needed. Can you please send me a private message including the full name as it appears on the account and your full name if different? 

To send me a Private Message, please click my name “ComcastAmira” and click “send a message. 

[ComcastAmira]

@chouinar, thanks for getting back to us on here about this concern. I appreciate you keeping this thread updated with what is going on. Please do let us know if you continue to experience this issue on your end and be sure to reach out to us for any future issues or concerns. I will follow up with you on Saturday to make sure that things are still looking good on your end as well. Do let me know if you need any assistance in the meantime. 

[joconnell97]

@ComcastAmira  - thanks for reaching out.  I sent you a message as requested.

[ComcastAmira]

@joconnell97, of course, I am here to help! I have responded to your private message and I look forward to your response. 

[chouinar]

New update, let it go for a week to see how it behaved. If I had to guess, it's about 70% fixed with the work the technician did last week. I no longer disconnect multiple times an evening, usually only 0-1 times, but video streams are still frequently interrupted. Reached out and will have a call with T2 support sometime in the next two days.

[ComcastAmira]

@chouinar, we thank and appreciate you for keeping us updated on this! Did you happen to get back into contact with T2 support regarding this? 

[ComcastAmira]

@chouinar, I have not heard back from you on here or in our private message, so I will be locking this thread. Please send me another PM if you still need assistance with this internet concern. Please create a new Public post for any new issues or concerns, we're here to help. Thanks and we appreciate you being the best part of Comcast.